More reliable means of communications are being continuously developed. Radio waves particularly are susceptible to disruption due to natural and man-made interferences. Unfortunately lives may be lost when such interferences might impede disaster relief and national defense communications since timely information can reduce indecision or initiate responsive action.
Oftentimes sensitive information from a data source and from vocal utterances quickly must be encrypted, processed, transmitted and decrypted for use. This process calls for a separation of the data into categories generally referred to as red information or black information. Red information, generally speaking, is classified plain-text that usually is found on the unencrypted side of data transmission or processing equipment. Black information is encrypted information. Thus a red/black concept refers to the electrical and electronic circuits, components, equipments, systems and so forth which handle classified plain-text information in electric signal form (red) which is separated from those parts of a system which handle encrypted information (black). Under this concept, red and black terminology designates such circuits, components, equipment systems and so forth and the areas in which they are contained.
A variety of so-called secured communications systems have evolved which profess to be able to handle classified, encrypted and unclassified information and which may or may not use redundant links for reliability. The communication switching system by Christian Jenny of U.S. Patent and Trademark Office, U.S. Pat. No. 3,970,994 discloses a distribution control having a register for each communication line. A plurality of processor modules are provided with a loop structured arrangement of interconnected branches on which data blocks can be transferred from each line register to and from each processor module. Another related patent to Jean Charpentier of the U.S. Patent and Trademark Office, U.S. Pat. No. 3,964,056 discloses a system which directs orders to peripheral devices in a data processing system having plural central control units. The system provides alternative routes through one central control unit to a peripheral in the event that the other loses access to the peripheral. In both of these cases there is no attempt made to separate the red from black information and neither concerns itself with providing for satellite relay of uhf information in the event of failure of the conventional hf link.
Thus, there is a continuing need in the state-of-the-art for a digital interface having uhf and hf communication links and which assures a separation of red and black information and, optionally, the ability to transfer information from another source such as a submarine.